During Cashman's tenure as Assistant GM and VP/General Manager, the Yankees have won seven American League pennants and five World Series championships. Despite the team's success, in 2005 Cashman considered leaving the Yankees due to conflicts with owner George Steinbrenner and organizational disputes between team officials in New York City and Tampa.[6] The Washington Nationals were rumored to be interested in hiring Cashman, which would have brought him back to the city where he attended school. Instead, Cashman agreed to a new contract with the Yankees following the conclusion of the 2005 season which gave him more authority in personnel decisions and paid him an average of $1.3 million more over the following three years.[7]

On September 30, 2008, he signed a new 3-year contract to stay with the Yankees through the 2011 season.[8] Following that season, when the Yankees failed to make the playoffs, Cashman signed CC Sabathia, AJ Burnett, and Mark Teixeira to long-term free agent contracts. These three players played a huge role in the Yankees season, culminating with a victory in the 2009 World Series.

The Yankees re-signed Cashman to a three-year deal in November 2011.[9]

During 2013, Cashman was involved with a tweet that Alex Rodriguez composed on Twitter. The tweet Rodriguez composed was regarding that he was cleared to play by his doctors after his hip surgery. Cashman was not pleased about the tweet claiming that the doctors did not give such authority to clear Rodriguez to play after seeking a second opinion with them.

On October 10, 2014, the Yankees signed Cashman to another three-year deal through the 2017 season.[10]

He currently lives in Darien, Connecticut with his family.[14] Cashman's wife, Mary, filed for divorce in February 2012; they had been reportedly separated for a year. The day prior, prosecutors charged a woman with stalking Cashman in an attempt to extort money regarding an extramarital affair.[15] Cashman is a New Jersey Devils fan.[16]